Create a new window and tabs

Create a window:

local Window = Library:CreateWindow({
    Title = 'Example menu',
    Center = true, -- Set Center to true if you want the menu to appear in the center
    AutoShow = true, -- Set AutoShow to true if you want the menu to appear when it is created
    TabPadding = 8,
    MenuFadeTime = 0.2
    --Position = float (optional)
    --Size = float (optional)
})

Create a tab

local mainTab = Window:AddTab('Main')

Just put this in the code

local LeftGroupBox = Tabs.Main:AddLeftGroupbox('Groupbox')